Ambient self-crosslinkable latex

ABSTRACT

The present invention relates to storage stable film forming latex particles substantially free of adipic acid dihydrazide (ADH) that crosslink under ambient conditions during or after drying. Monomers for the formation of the crosslinkable moieties in the latex particles include diacetone acrylamide (DAAM) or the likes and methacrylamide (MAM) or the likes with or without styrene. A paint composition comprising the storage stable latex particles was described.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. Non-provisionalpatent application Ser. No. 14/343,292 submitted on Mar. 6, 2014,entitled “Hydroxyethyl Cellulose Grafted Acrylic Latex” which claimspriority to International Patent Application No. PCT/US2012/055,883,filed Sep. 18, 2012, entitled “Hydroxyethyl Cellulose Grafted AcrylicLatex” which claims priority to the U.S. Provisional Application No.61/536,264, filed Sep. 19, 2011, entitled “Hydroxyethyl CelluloseGrafted Acrylic Latex.” The contents of all parent applications areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

This invention generally relates to aqueous latex compositionscomprising self-crosslinkable polymer emulsions and methods forpreparing same, as well as products formed with said composition.Specifically, the invention involves a novel crosslinking mechanisminvolving diacetone acrylamide and methacrylamide but that does notrequire the presence of adipic dihydrazide (ADH).

BACKGROUND OF THE INVENTION

There is increasing societal sensitivity to environmental issues,including restrained use of organic solvents, volatile organic compounds(VOCs) and other additives such as coalescent agents due to healthconcerns. One area in which the foregoing has become important isarchitectural coatings, especially aqueous latex paints and water bornecoating compositions. As a result, aqueous latex paints and water bornecoating compositions are gaining popularity.

In practice, however, it is a challenge to minimize the use of organicsolvents, VOCs and additives without diminution of the performance ofthe coatings. Coalescence is a process whereby polymer particles in anaqueous latex or dispersion come into contact with one another duringfilm-forming process and polymer chains diffuse across boundaries oflatex/dispersion particles to yield continuous films with good bondingof the polymer particles. There is a balance between achieving thedesired hardness of a resulting dried film from an aqueous paintcomposition and having the proper coalescence.

A method of improving the properties of films formed by water-bornecompositions is to include polymer latex particles that are capable ofbeing crosslinked. In one example, diacetone acrylamide (DAAM) isincluded in the latex particles as moieties. Crosslinking agents withinthe aqueous composition but not part of the latex particles can be usedto crosslink the polymer latex particles when the aqueous composition isapplied to a substrate under ambient conditions. Adipic dihydrazide(ADH) is one of these crosslinking agents that have been used foraqueous latex polymers. However, the conventional approach of usingdiacetone acrylamide (DAAM) as part of the latex and adipic dihydrazide(ADH) as free floating agents in the aqueous composition sometimesallows crosslinking reactions between the DAAM and ADH to take placeduring storage, i.e., while the latex particles are in the aqueousphase. This may diminish shelf stability and reduce intra particlecrosslinking under ambient drying conditions. Other conventionaltwo-component crosslinking approaches have similar stability issues aswell as VOC and odor concerns.

U.S. Pat. No. 3,838,104 to Hayashi et al. discloses an oil andwater-repellent copolymer by copolymerizing diacetone acrylamide (DAAM),diacetonemethacrylamide (DAMAM) or a lower alkylol derivative thereofand a fluoroalkyl monomer. Hayashi does not disclose an aqueous latexcomposition that may crosslink when applied to a substrate under ambientconditions. CN 101348541 to Li discloses a crosslinking acrylatecomposite emulsion. The functional monomers include diacetone acrylamide(DAAM) and adipic dihydrazide (ADH). U.S. Pat. No. 3,451,480 to Zehdiscloses a copolymer of acrylamide and diacetone acrylamide (DAAM) as afriction reducer in brines used in oil well fracturing. Up to 0.006% ofN,N′-methylene bisacrylamide may be included as a cross-linking agent.WO 03/068880 A1 describes a latent cross-linking thickener compositionincluding diacetone acrylamide (DAAM) and adipic dihydrazide (ADH).

Lu et al. (Zhongguo Jiaonianji, 15 (1), 2006, pp. 17-20) describes ablend of self-crosslinking acrylate latexes. Each of the latexes iscopolymerized from diacetone acrylamide (DAAM), acrylamide (AM) orN-methylacrylamide, among other monomers. However, a blend of DAAMcontaining copolymer with an AM containing copolymer shows a lack ofwater resistance. U.S. Pat. No. 3,497,467 to Coleman discloses anaqueous polymer latexes having diacetone acrylamide (DAAM) monomer asthe main component. The DAAM dominant polymer can be a copolymer with avinyl or another acrylic monomer. WO 02/087734 A1 discloses hydrophobicmembranes modified with a surface coating that includes a cross-linkedter-polymer. The monomers include diacetone acrylamide (DAAM),N,N′-methylenebisacrylamide and N,N-dimethylacrylamide.

All patents and publications discussed herein are incorporated byreference herein in their entirety.

There remains an unmet need for an aqueous latex composition that isstable during storage while still being capable of crosslinking whenapplied on a substrate without additional water borne crosslinkingagents such as ADH during or after drying under ambient conditions.Crosslinking after film formation would improve film strength, block andwater resistances and bring other benefits to the water borne coatingsall while achieving proper film formation.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a latexcomposition that remains substantially free of crosslinking reactionsduring storage, thus having improved shelf life, but that allowsself-crosslinking to occur under ambient conditions after application toa substrate. In one embodiment, the object is achieved by an inventiveaqueous composition comprising latex particles polymerized fromprincipally acrylic and/or vinyl acrylic monomers with moieties ofdiacetone acrylamide (DAAM) monomers or the likes and methacrylamide(MAM) monomers or the likes, wherein the latex particles crosslink whenthe water content is reduced or substantially depleted under ambientconditions by drying or evaporation. Preferably, the inventiveself-crosslinkable latex particles can crosslink substantially without acrosslinking agent such as adipic dihydrazide that would reside in thewater component.

It is another object of the present invention to provide an aqueouscore/shell latex composition which crosslinks during or after theevaporation of water.

It is still yet another object of the present invention to provide anaqueous composition comprising latex particles having a C₄-C₁₈ethylenically unsaturated monomer moiety containing a ketone and aC₃-C₁₈ ethylenically unsaturated monomer moiety containing a primaryamide, wherein the ketone is substantially unreactive to the primaryamide when the latex is in storage in an aqueous solution and whereinthe ketone reacts with the primary amide and latex particles crosslinkwhen water is at least partially removed from the latex under ambientconditions substantially without a water borne cross-linking agent.

One embodiment of the present invention is directed to an aqueouscomposition comprising latex particles, which comprise a film formingmonomer, a C₄-C₁₈ ethylenically unsaturated monomer moiety containing aketone and a C₃-C₁₈ ethylenically unsaturated monomer moiety containinga primary amide. The ketone is substantially unreactive to the primaryamide when the latex particles are in storage in water and wherein theketone reacts with the primary amide and latex particles crosslink whenwater is at least partially removed from the latex particles underambient conditions. The monomer containing a ketone can be diacetoneacrylamide, diacetone methacrylamide, or acetoacetoxyethyl methacrylate,or combinations thereof. The monomer containing a primary amide can bemethacrylamide and/or acrylamide.

Another embodiment of the present invention is directed to an aqueouscomposition comprising film forming latex particles having crosslinkingmoieties. The crosslinking moieties comprise a diacetone acrylamidemoiety and a methacrylamide moiety. The latex particles cross-link whenapplied to a substrate at ambient conditions. In one aspect of thepresent invention, the composition is substantially free of adipic aciddihydrazide or the like.

The film forming latex particles preferably comprise acrylic latexparticles. Alternatively, the film forming latex particles may alsocomprise at least about 75% acrylic or vinyl monomers. The ratio byweight of diacetone acrylamide to methacrylamide ranges from about 20:1to about 1:20 by weight, preferably from about 6:1 to about 1:3, morepreferably from about 4:1 to about 1:2.

A ratio by weight of diacetone acrylamide and methacrylamide to filmforming monomers ranges from about 0.1:100 to 10:100, preferably fromabout 0.5:100 to 5:100, more preferably from about 1:100 to 3:100. Thelatex particles may have a molecular weight from about 20K to about 500KDaltons based on GPC measurement, preferably from about 80K to about300K Daltons based on GPC measurement.

The latex particles should have a MFFT from about −10° C. to about 50°C., more preferably from about −5° C. to about 25° C.

The present invention is also directed to an aqueous compositioncomprising core shell latex particles having a shell polymer comprisingdiacetone acrylamide and methacrylamide moieties, wherein the latexparticles crosslink when applied to a substrate at ambient conditions.Preferably, the core polymer has a diacrylate crosslinker.

DETAILED DESCRIPTION OF THE INVENTION

In a preferred embodiment of the invention, self-crosslinking latexpolymers and resins can advantageously comprise at least a pair ofcrosslinkable functional groups or moieties that are reactive with oneanother under ambient conditions in the absence of water or reducedwater content to form a covalent bond, but which are substantially notreactive with each other during storage in water, and the ambientself-crosslinking occurs preferably without a crosslinking agent(s) thatresides in the water. These crosslinking agents such as ADH are reactiveand can cause crosslinking of the latexes while suspended in water.Other compounds may be needed in the composition to control thereactivity of the crosslinking agents, which may also have unpleasantodors.

As discussed in the parent application PCT/US2012/055,883, the presentinventors have discovered that when methacrylamide (MAM) and a ketonefunctionalized acrylamide, such as diacetone acrylamide (DAAM), are usedin predetermined amounts as monomers for the latex polymer suspended inwater they act as self-crosslinking moieties under ambient conditions.After the latex compositions are applied on a substrate or surfacewithout using heat or dryers, a crosslinking reaction takes place.

However, substantially no crosslinking reaction in the aqueous phaseoccurs during storage. Without being bound to any particular theory, thepresent inventors believe that the self-crosslinking reaction occursthrough particle-to-particle or inter-polymer chain interactions of thefunctional groups, e.g., methacrylamide and diacetone acrylamidemoeities, incorporated onto the polymer chains. Molecularinter-diffusion between neighboring latex particles, which is importantfor the generation of latex film strength takes place prior to thecrosslinking reaction. However, strongly crosslinked particles areunable to inter-diffuse. It is also believed that the primary amidenitrogen on the methacrylamide unit may react with the carbonyl group ofthe diacetone acrylamide unit or other active carbonyl groups to form animine linkage Inter-chain hydrogen bonding and chain entanglements arealso likely to be present, which further enhances the mechanicalstrength of the film. The hydroxyl group in hydroxyethyl cellulose (HEC)grafting may also play certain functions for the ambient crosslinking inour system.

In one embodiment, diacetone acrylamide (DAAM) or diacetonemethacrylamide (DAMAM) monomer is copolymerized as part of the latexparticles and functions as a self-crosslinking moiety. Instead of or inaddition to DAAM, diacetone methacrylamide (DAMAM) and/oracetoacetoxyethyl methacrylate (AAEM) can be used singly or with eachother.

In another embodiment, methacrylamide (MAM) and/or acrylamide (AM)monomer is copolymerized as part of the latex particles and functions asanother self-crosslinking moiety.

In one preferable embodiment, latex particles are polymerized from filmforming monomers, including diacetone acrylamide (DAAM) andmethacrylamide (MAM) in a predetermined ratio relative to each other(DAAM/MAM) and in an amount together (DAAM+MAM) relative to the totalamount of the film forming monomers by weight. Film forming monomers arethe monomers that form the dried polymeric film or dried paint layer(polymeric film, pigments and colorants, etc.). Suitable film formingmonomers include but are not limited to vinyl monomers, acrylic monomersand styrene monomers, discussed in detail below. These monomers arepolymerized to form latex particles suspended in an aqueous solution,which cross-link to each other to form a film or paint layer. In oneembodiment, the film forming monomers do not include the crosslinkablemonomers/moieties discussed above, such as DAAM, DAMAN, AAEM, MAM or AM.

Preferably the ratio by weight of diacetone acrylamide or the likes(e.g., DAMAM or AAEM) to methacrylamide or the likes (e.g., acrylamide)in the latex particles ranges from about 20:1 to about 1:20 by weight.More preferably the ratio by weight of diacetone acrylamide tomethacrylamide in the latex particles ranges from about 6:1 to about1:3. Most preferably the ratio by weight of diacetone acrylamide tomethacrylamide in the latex particles ranges from about 4:1 to about1:2. Said ratio can also be from about 10:1 to 1:10, or 4:1 to 1:2 or2:1 to 1:1 by weight.

Preferably the weight ratio of diacetone acrylamide and methacrylamideto the film forming monomers ranges from about 0.1:100 to 10:100. Morepreferably, the ratio of the weight of diacetone acrylamide andmethacrylamide to the film forming monomers ranges from about 0.5:100 to5:100. Most preferably the ratio of the weight of diacetone acrylamideand methacrylamide to the film forming monomers ranges from about 1:100to 3:100.

The present invention also relates to the impact of the crosslinking onthe properties of the coating or film formed from the composition,particularly on the mechanical, chemical, physical, and physico-chemicalproperties of the coating. These properties can include, but are notlimited to, the minimum film forming temperature (“MFFT”), blockresistance, scrub resistance, molecular weight, pencil hardness,viscosity, water resistance, water stain resistance, scratch resistance,shelf/incubation stability, and the like, and combinations thereof.

Preferably acrylic monomers principally form the latex particles thatthe MAM and DAAM form moieties thereon. Any acrylic monomers can be usedin the present invention. Suitable acrylic monomers include, but are notlimited to methyl acrylate, ethyl acrylate, methyl methacrylate, andethyl methacrylate, butyl acrylate and butyl methacrylate, iso-octylmethacrylate and acrylate, lauryl acrylate and lauryl methacrylate,2-ethyl hexyl acrylate, stearyl acrylate and methacrylate, isobornylacrylate and methacrylate, methoxy ethyl acrylate and methacrylate,2-ethyoxy ethyl acrylate and methacrylate, 2-hydroxyethyl acrylate,2-hydroxybutyl, dimethylamino ethyl acrylate and methacrylate,acrylates, alkyl(meth)acrylic acids such as methyl acrylic acids, wetadhesion monomers, such as N-(2-methacryloyloxyethyl)ethylene urea, andmultifunctional monomers such as divinyl benzene, diacrylates, forcrosslinking functions etc., acrylic acids, ionic acrylate salts,alkacrylic acids, ionic alkacrylate salts, haloacrylic acids, ionichaloacrylate salts, acrylamides, alkacrylamides, monoalkyl acrylamides,monoalkyl alkacrylamides, alkyl acrylates, alkyl alkacrylates,acrylonitrile, alkacrylonitriles, dialkyl acrylamides, dialkylalkacrylamides, hydroxyalkyl acrylates, hydroxyalkyl alkacrylates, onlypartially esterified acrylate esters of alkylene glycols, only partiallyesterified acrylate esters of non-polymeric polyhydroxy compounds likeglycerol, only partially esterified acrylate esters of polymericpolyhydroxy compounds, and combinations thereof. The alkyl methacrylatemonomer is preferably methyl methacrylate.

Preferred monomers containing aromatic groups are styrene andα-methylstyrene. Other suitable monomers containing aromatic groupsinclude, but are not limited to, 2,4-diphenyl-4-methyl-1-pentene,2,4-dimethylstyrene, 2,4,6-trimethylstyrene,2,3,4,5,6-pentafluorostyrene, (vinylbenzyl)trimethylammonium chloride,2,6-dichlorostyrene, 2-fluorostyrene, 2-isopropenylaniline,3(trifluoromethyl)styrene, 3-fluorostyrene, α-methylstyrene,3-vinylbenzoic acid, 4-vinylbenzyl chloride, α-bromostyrene,9-vinylanthracene, and combinations thereof.

Preferred monomers containing primary amide groups are methacrylamide,and acrylamide. Other suitable monomers containing amide groups include,but are not limited to, N-vinylformamide, or any vinyl amide,N,N-dimethylacrylamide, N-(1,1-dimethyl-3-oxobutyl)(meth)acrylamide,N-(hydroxymethyl)(meth)acrylamide, N-(3-methoxypropyl)acrylamide,N-(butoxymethyl)acrylamide, N-(isobutoxymethyl)acryl(methacryl)amide,N-[tris(hydroxymethyl)methyl]acryl(methacryl)amide,7-[4-(trifluoromethyl)coumarin](meth)acrylamide,3-(3-fluorophenyl)-2-propenamide, 3-(4-methylphenyl)acrylamide,N-(tert-butyl)(meth)acrylamide, and combinations thereof. These monomerscan be polymerized with acrylic monomers, listed above. General formulafor vinyl(form)amides:

and (meth)acrylamides:

where R1 is H, CH₃, CH₂CH₃, or other substituted functional groups, andR2 can be —H, —CH₃, —CH₂CH₃, and other substituted organic functionalgroups.

Suitable styrene monomers include, but are not limited to, styrene,methylstyrene, chlorostyrene, methoxystyrene and the like. In thisembodiment, styrene monomers are preferably co-polymerized withmethacrylamide and acrylamide monomers.

In one embodiment, the aqueous latex polymer may also comprise vinylmonomers. Monomers of this type suitable for use in accordance with thepresent invention include any compounds having vinyl functionality,i.e., —CH═CH₂ group. Preferably, the vinyl monomers are selected fromthe group consisting of vinyl esters, vinyl aromatic hydrocarbons, vinylaliphatic hydrocarbons, vinyl alkyl ethers and mixtures thereof.

Suitable vinyl monomers include vinyl esters, such as, for example,vinyl propionate, vinyl laurate, vinyl pivalate, vinyl nonanoate, vinyldecanoate, vinyl neodecanoate, vinyl butyrates, vinyl caproate, vinylbenzoates, vinyl isopropyl acetates and similar vinyl esters; nitrilemonomers, such acrylonitrile, methacrylonitrile and the like; vinylaromatic hydrocarbons, such as, for example, styrene, methyl styrenesand similar lower alkyl styrenes, chlorostyrene, vinyl toluene, vinylnaphthalene and divinyl benzene; vinyl aliphatic hydrocarbon monomers,such as, for example, vinyl chloride and vinylidene chloride as well asalpha olefins such as, for example, ethylene, propylene, isobutylene, aswell as conjugated dienes such as 1,3-butadiene, methyl-2-butadiene,1,3-piperylene, 2,3-dimethyl butadiene, isoprene, cyclohexene,cyclopentadiene, and dicyclopentadiene; and vinyl alkyl ethers, such as,for example, methyl vinyl ether, isopropyl vinyl ether, n-butyl vinylether, and isobutyl vinyl ether.

Preferably, the film forming monomers are the principal monomers in thelatex and the two crosslinkable moieties make up small portions of thelatex, as discussed in the ratios above. The film forming monomerspreferably make up more than about 75% by weight of the latex particles,more preferably more than about 85% and more preferably more than about90%.

The present inventors have conducted a number of experiments to show theefficacy of the self-crosslinkable polymer latex with at least two typesof crosslinkable moieties. Each moiety may exist at multiple locationsin the latex particles. These moieties may crosslink a single latexparticle to itself (intra particle cross-linking); however as shown inthe Examples below, they could crosslink to other latex particles (interparticle cross-linking) to form a strong paint film. It is noted thatExamples 1-6 discussed below were reported in the parent PCTinternational application as Examples 4, 5A, 5B, 6, 8 and 9,respectively. As discussed below, these examples and others illustratethe inventive use of the MAM and DAAM moieties to crosslink latexpolymers.

The crosslinking is demonstrated by measuring water sensitivity of driedlatex films. The procedure for the water sensitivity test is describedin the Material and Methods section, as shown below. Films were driedunder ambient conditions before the water sensitivity test wasperformed. The results for the water sensitivity tests for latexes fromExamples 1-3 are shown below. In Example 1 the latex contains bothdiacetone acrylamide (DAAM) and methacrylamide (MAM) moieties in thecomposition; Example 2 contains MAM but not DAAM moiety; and Example 3contains DAAM but not MAM. As shown below, the dried film of Example 1has significantly better water resistance, suggesting significantly morecrosslinking when DAAM is used with MAM even when no heat or dryer isused. In contrast, when either one of these two components, DAAM andMAM, is omitted as in the cases of Examples 2 and 3, the resulting driedlatex is very sensitive to water, which means that the crosslinking isunsatisfactory. No crosslinking agent, such as ADH, is added to theaqueous composition in Examples 1-3. Comparative Experiment A shows theresults of water sensitivity tests performed on latex films of Examples1-3 made with the inventive latex.

Examples 4, 5 and 6 all have MAM/DAAM crosslinking moieties in additionto hydroxyl cellulose (HEC) in the composition. Example 5 and 6 furthercontains methylol methacrylamide monomer to improve latex stability andthe dried film's water permeability.

The self-crosslinking under ambient conditions when the latex is coatedon a substrate using the DAAM/MAM does not require any dryer, or acrosslinking agent in water phase, e.g. ADH, to initiate thecrosslinking. This novel combination also minimizes the volatile organiccompounds (VOC) or odor issues associated with conventionaltwo-component approaches, such as DAAM in the latex and adipicdihydrazide (ADH) in the water phase discussed above. Meanwhile itimproves the film's mechanical strength, and extends the storage life ofthe latex in the aqueous phase. Preferably, the latex composition issubstantially free of water borne crosslinking agents, such as adipicdihydrazide or the like. Water molecules appeared to play a significantrole in latex stability. The premature crosslinking reactions aresignificantly restricted in the presence of water, probably becauseparticle-particle inter-diffusions or inter-chain interactions arehindered. The latex sample disclosed in Example 1 remains stable evenafter one year Of storage and the dry film formed from this aged latexstill exhibits excellent water sensitivity and crosslinking ability.

The performances in terms of the scrub resistance, block resistance,water sensitivity, and water stain are related to crosslinking. A paintfrom a commercial latex which does not contain any DAAM or MAMfunctional monomers in its composition was used as a control forcomparison with paints made from inventive latex samples of Examples7-10 as shown in Comparative Experiment B. The control sample did notform a cross-linked dry film and has relatively poor scrub resistanceand water sensitivity compared with the paints made with inventivelatexes of Examples 7-10 which are incorporated with self-crosslinkingfunctional monomers DAAM and MAM, but which are substantially free ofADH. The results clearly demonstrate that the addition of DAAM and MAMas a functional moiety pair to the polymer chains constitutes a novelapproach to achieve ambient cross-linking without a crosslinking agentin the water phase such as adipic dihydrazide (ADH).

Example 11 shows an inventive core/shell latex with the DAAM and MAMmoieties in the shell and Examples 12 to 14 show core/shell latexes withonly one DAAM or MAM moiety. These latexes are prepared in a two-stageprocess, allowing additional control over the composition and structureof the polymer films. The first stage process produces a core of thelatex and the second stage provides a shell for the latex. The core isprovided with a non-ambient crosslinker (also called crosslinkingmonomers), e.g. 1,4-butanediol diacrylate (i.e. SR-213) in thepre-emulsion composition and no MAM or DAAM is present in the firststage pre-emulsion composition. The crosslinking of the core polymersimparts improved hardness and weathering property to the resultinglatex.

In Example 11, the shell contains both DAAM and MAM moieties and thelatex is capable of crosslinking when the aqueous environment is atleast partially depleted of water. The shell composition of Example 12is different from Example 11 only in that the former contains no MAMmonomer in the pre-emulsion composition. On the other hand, shellcompositions of Examples 13 and 14 lack DAAM in contrast to Example 11.Example 14 is further different from Example 11 in that the BA monomeris replaced with 2-EHA.

Comparative Experiment C shows the physical and mechanical properties ofpaint samples made from the core-shell latexes in Examples 11-14. Thiscomparative experiment shows the efficacy of having the DAAM and MAMmoieties on the shell or second phase of the core-shell latex. Itdemonstrates the effectiveness of ambient curing/crosslinking usingblock resistance as an indicator. A paint film was drawn down on aLeneta card for each latex sample. It was dried for 7 days at roomtemperature before being placed into a 120° F. oven for 24 hours. Theblock resistance was rated on a numerical scale of 1 to 5 with 5 beingthe best. The block resistance test was conducted according toASTM_D4946-89. The results for the above examples demonstrated that theMAM/DAAM moiety pair formed a cross-linked networks effectively atambient temperature, which improved the block resistance of the paintsample made with inventive Example 11.

The paint sample with the MAM and DAAM crosslinking pair shows superiorphysical and mechanical properties in comparison with a control paintsample without any crosslinkers. Comparative Experiment D compares theperformance of paints made from inventive examples 15 and 16, both ofwhich have MAM/DAAM crosslinkers with control paint Example I, whichdoes not use a crosslinking latex. While both paints using inventivelatex have the same block resistance as the control paint Example Iwhich does not have any crosslinker, they show other superior mechanicaland physical properties.

The effectiveness of the inventive crosslinking between MAM and DAAMmoieties was further compared in Comparative Experiment E with a paintsample that uses a single conventional crosslinking moiety, such asDAAM, and a crosslinking agent, such as ADH, in the water phase. Theperformance of these two paints is comparable. The inventive paint ismade of Example 16 latex and contains the MAM and DAAM crosslinkingmoiety pair. The paint control Example II is made of a latex containingthe DAAM moiety and the ADH crosslinking agent in the water phase. Thisresult shows that the scrub resistance of the paints using the inventivelatex containing MAM and DAAM is somewhat better than the paint usinglatex containing DAAM and ADH in the water phase and the waterresistances of the two paint samples are identical.

More direct evidence for the self-crosslinking of the latex underambient conditions is provided by Examples 17 and 18. The molecularweights of the samples were measured on a GPC instrument from WATERSCorp. The molecular weight analysis was first performed on the latexsamples before curing. Then, the latex samples were drawn into a threemil thickness film and dried. It is observed that there were insolublegels for both samples in the solvent used for the Mw analysis and thegels would not dissolve even by solvent heating. Molecular weightanalysis fig the soluble portion of the 7-day cured film was made. Thepresence of the insoluble gel even at an elevated temperature (inTetrahydrofuran-THF solvent and about 70° C.) is consistent with thecrosslinking of the latex and make it difficult to dissolve, i.e., thusimproving solvent resistance. The polymer converts to thermoset matrixafter it is cross-linked and loses its chain mobility. One of thepolymer thermoset features is the superior solvent/chemical resistance,which renders it non-soluble or difficult to dissolve in strong organicsolvent. It is also common practice to measure the degree ofcrosslinking through solvent solubility test and swell ratiomeasurement.

The soluble portions of the two cured samples also show increasedmolecular weights. For the cured sample from Example 17, the molecularweight of the soluble portion increases from 161K to 178K. The samplefrom Example 18 shows a similar degree of increase, from 159.2K to180.3K. This result is consistent with the crosslinking of the polymers,resulting in an increase of the measured molecular weight.

Without being bound to any particular theory, the present inventorsbelieve that in a conventional two-component cross-linking system, suchas in the case of DAAM and ADH, component ADH is water soluble and canmove freely in the aqueous latex compositions or paints. ADH orhydrazide containing particles can then react with the DAAM resulting inpremature crosslinking while the aqueous latex compositions or paintsare still in storage. In contrast, in the inventive DAAM and MAMcrosslinking system, both the DAAM and MAM units are moieties or partsof the latex particles and water acts to separate the latex particlesaway from each other thereby inhibiting cross-linking while beingdispersed in water. On the other hand, when the latex is drying ordried, the DAAM and MAM moieties can react more readily resulting inbetter mechanical strength of the dry film as demonstrated in Example 1.

It is to be understood that the present approach is not limited to theDAAM and MAM combination but can be tailored to different functionalgroup combinations for many other applications. Although there may besome limited intra-particle/intra-chain crosslinking, the presentinventors believe that the majority of the crosslinking reactions occurwhen the latex particles inter-diffused in contact with neighboringparticles during the drying and coalescence process. This conclusion issupported by the observations that a latex sample of Example 1 which hasstored for one year still maintained its crosslinking ability, when itwas coated on a substrate under ambient conditions as described above.

As used herein, the term “substantially free” or “substantiallywithout”, referring to a component in a composition, mean that thecomposition comprises not more than about 1 wt %, preferably not morethan about 0.5 wt %, more preferably not more than about 0.1 wt %, mostpreferably not more than about 0.02 wt %, or in some cases completelynone (about 0%), of the component.

The present invention may be understood more readily by reference to thefollowing description of the invention, and to the Examples includedtherein.

Before the present compositions of matter and methods are disclosed anddescribed, it is to be understood that this invention is not limited tospecific synthetic methods or to particular formulations, unlessotherwise indicated, and, as such, may vary from the disclosure. It isalso to be understood that the terminology used is for the purpose ofdescribing particular embodiments only, and is not intended to limit thescope of the invention.

EXAMPLES

Material and Methods

Particle size distribution is determined by Microtrac 250 particle sizeanalyzer using light scattering technology. Particle size means anaverage particle size based on the diameter of the particles.

Rheological curves are measured by a Bohlin CVO Rotational Viscometer(0.5° cone and 40 mm diameter plate).

The water sensitivity test (1 minutes and 5 minutes water spot test) isillustrated by the following procedures. Emulsion latex samples weredrawn down on a sealed Leneta card (made by BYK for example) to form adry film using a BYK-GARDNER 3 MIL WET FILM draw down bar. The latexfilm was air-dried on a flat horizontal surface for one week beforetesting. To the dried film surface, 3-5 drops of water were placed andthe water sensitivity of the latex film was rated using the finger nailscratching method for rating the dry film strength after 1 minute and 5minute soaking periods. The wet films are rated for resistance to fingernail scratching from 1 to 5, with 5 being the best.

The water stain resistance is tested by a visual rating of water stainon the dried paint film. A 3 mil film of paint is dried for 7 days atroom temperature, and 3 ml of DI water is placed on the horizontal driedpaint film for 3 minutes, and then the Leneta card is raised to avertical position to allow water to flow down across the surface of thefilm. The film is placed in a vertical position while the waterevaporates. The water stain mark on the film surface is visuallyinspected and assigned a number from 1 to 5, 5 being the best and 1being the worst.

Water vapor permeability for grafted and control acrylic latex sampleswas measured by an internal method which followed the procedures givenby the ASTM D1653-93 method (standard test methods for water vaportransmission of organic coating films). The test specimen was sealed tothe open mouth of a cup or dish containing water, and the assembly wasplaced in a controlled atmosphere environment at constant humidity andtemperature. The permeability cups used for the testing were BYK-GardnerPO-2301 (25 cm²) and the parchment paper for vapor permeability testwere from All-State International, Inc. The drawdown films were made ona parchment paper using the latex samples with a 3-mil drawdown′bar andthen the films were dried for one week before the water vaporpermeability measurement. The dried film was cut into a proper size forthe cup, the thickness of the film and paper was measured, and theweight of each coating sample was recorded. The permeability cup wasfilled with deionized water and the opening was sealed with the dryfilm. The samples were weighed to the 0.0001 g accuracy before and after24 hours evaporation. The permeability was calculated using the formulaedefined in section 13 of ASTM method D1653-93.

The molecular weights were measured on a GPC instrument from WATERSCorp. The molecular weight analysis was performed on the latex samples(before curing). The latex samples were then drawn into three milthickness films and dried for 7 days. The molecular weights of curedsamples were measured on the soluble portion in THF solvent. Themolecular weights reported are all weight average molecular weightsusing polystyrene calibration standards.

As used herein, MFFT is the minimum temperature at which the latex willform a continuous film. MFFT was determined on a MFFT Bar-90 fromRhopoint Instruments according to ASTM D2354-98 and ISO 2115:1996)(American Standard Test Method for Minimum Film Formation Temperature).The emulsions were applied using a 75 micron cube applicator to formtracks. Emulsions were allowed to dry for 3 hours. The MFFT weredetermined as points on tracks where the film has coalesced over 90% ofthe track width (no cracking).

The MFFT of the inventive latexes range from about −10° C. to about 50°C., preferably about −5° C. to about 28° C., more preferably about 2° C.to about 25° C. and most preferably about 4° C. to about 18° C.

Block resistance, or the propensity of a coating to adhere to itselfinstead of to its substrate, was measured according to a modifiedversion of ASTM D4946-89. On a sealed white Leneta™ WK card, a 3 milthick coating was prepared. After one week of drying at roomtemperature, the coating was cut into four one inch squares. Two of thesquares were oriented face to face (i.e., coated sides touching) and areplaced under a 100-gram weight in a 120° F. oven for about 24 hours. Theother two of the squares were oriented face to face and placed under a100-gram weight at room temperature for about 24 hours. Both sets offace to face squares were then allowed to equilibrate to ambienttemperature for about ½ hour. Each set of squares was then pulled apartusing a slow and steady force, forming a T pattern. Block resistance wasrated based on the percentage of area of the paint on one surface thatwas transferred to the other surface. 0% transfer indicates a perfectblocking resistance while 100% transfer indicated paints on both sidesare completely stuck together.

The residual monomers were measured by a gas chromatography (GC)instrument equipped with a FID or a Mass detector. This method is theindustry accepted standard procedure for testing residual monomers, andis known to those of ordinary skill in the art.

Scrub Test. The scrub resistance is determined by ASTM Method D2846. Inthis test, a 7 mil drawdown of paint(s) is prepared on a scrub panel andallowed to air dry at room temperature for one week. A medium bristlebrush is soaked overnight in deionized water for conditioning prior torunning the test. Two glass plates are placed in the tray of theAbrasion tester, and three brass shims are placed on the plates in sucha way that each paint being tested would have a shim under it. The testpanel with the dried paint is secured to the two glass plates on theGardner Abrasion Tester. Ten grams of abrasive scrub medium are appliedto the bristles of the brush and the brush is then placed in a brushholder which is secured to the cables of the Abrasion Tester. Five cc ofdeionized water is applied to the test panel, and the scrub cycles arestarted. Every 400 cycles another 10 g of abrasive medium is applied tothe brush and another 5 cc of deionized water is applied to the panel.The test is continued until paint is removed in one continuous lineacross its own shim and the number of cycles required to reach thispoint is recorded.

Examples Monomers (grams) 1 2 3 4 5 6 7 8 9 10 MMA 270.5 290.0 300.6259.3 265.3 278.7 254.0 270 251.0 265.3 BA 310.9 309.0 374.4 322.5 306.6252.7 311.0 310 308.0 307.4 2-EHA 23.2 25.6 84.3 19.2 MAA 4.7 4.4 6.25.2 5.4 5.3 4.7 4.8 5.4 5.5 AA Vinyl neodecanoate (VeoVa ™ 10) Styrene29.5 12.9 40.0 29.8 38.6 29.5 51.5 12.8 N-(2-methacryloyloxyethyl) 25.726.3 17.5 25.9 25.6 11.7 26.5 25.7 25.8 25.6 ethylene urea N-Methylolmethacrylamide 7.4 7.8 DAAM 2.9 3.4 2.9 2.9 2.6 4.5 2.9 0.7 2.9 MAM 2.52.6 2.5 2.6 5.2 1.8 2.5 3.2 2.5 1,4-butanediol diacrylate (i.e. SR-213)DAAM & MAM to total latex 0.84 0.40 0.44 0.83 0.86 1.20 0.98 0.84 0.600.84 monomers DAAM/MAM ratio 1.16 1.16 1.12 0.50 2.50 1.16 0.22 1.16Test of paints † † † ‡ ‡ ‡ ‡ † See Comparative Experiment A ‡ SeeComparative Experiment B

Examples 11 12 13 14 Monomers (grams) Stage1 Stage2 Stage1 Stage2 Stage1Stage2 Stage1 Stage2 15 16 17 18 MMA 284.0 330.0 284.0 330.0 284.0 330.0284.0 330.0 430.0 430.0 675.5 676.5 BA 118.4 281.0 118.4 281.0 118.4281.0 435.0 424.0 606.0 603.0 2-EHA 118.4 281.0 MAA 10.2 10.2 10.2 10.29.0 8.2 14.0 AA 4.0 4.0 4.0 4.0 Vinyl neodecanoate 460.1 460.1 460.1460.1 (VeoVa ™ 10) Styrene 27.1 N-(2- 21.3 21.3 21.3 21.3 19.2 18.2 30.630.6 methacryloyloxyethyl) ethylene urea N-Methylol methacrylamide DAAM1.6 1.6 8.3 12.2 18.2 22.5 MAM 1.2 1.2 1.2 5.5 2.8 4.2 5.11,4-Butanediol 1.6 1.6 1.6 1.6 diacrylate (i.e. SR-213) DAAM & MAM tototal 0.25 0.15 0.11 0.11 1.52 1.63 1.66 2.06 latex monomers DAAM/MAMratio 1.33 1.51 4.36 4.33 4.41 Test of paints § § § § §§ §§ § SeeComparative Experiment C §§ See Comparative Experiments D and E

Example 1

To a 5-liter 4-necked round bottom glass reactor equipped with amechanical stirrer, a thermocouple, a condenser, and nitrogen purge,445.0 g of deionized (DI) water and 2.0 g of emulsifier which is abranched sodium dodecylbenzene sulfonate (i.e., Rhodacal® DS-4 std),were added and heated to 79° C.

To an Erlenmeyer flask, the following ingredients were added and stirredto form a stable monomer pre-emulsion. Monomer pre-emulsion composition:

Methyl methacrylate (MMA) monomer 270.5 g Butyl acrylate (BA) monomer310.9 g Methacrylic acid (MAA) monomer  4.7 g Methacrylamide (MAM)monomer  2.5 g Diacetone acrylamide monomer (DAAM)  2.9 g Styrenemonomer  29.5 g N-(2-methacryloyloxyethyl) ethylene urea  25.7 g DIwater 210.0 g Sodium dioctyl sulfosuccinate surfactant (75% active)  2.2g Tetrasodium N-(1,2-dicarboxyethyl)-N-octadecyl  3.8 g sulfosuccinamatesurfactant (35% active) Ammonium salt of phosphate ester surfactant(100%)  1.0 g

Suitable surfactants include AEROSOL® 22 and AEROSOL® OT-75 made byCytec Industries and POLYSTEP TSP-16PE. About 1.9 g of ammoniumhydroxide (28%) was also added to the monomer mix for pH adjustment.

About 10 ml of 12.8% aqueous potassium persulfate (KPS) initiatorsolution and 35.0 g of the monomer pre-emulsion were charged to thereactor at 79° C. to form seed particles. After about 20 minutes at 79°C. with agitation, the delay feed of the monomer pre-emulsion togetherwith 30 ml of 4.2% aqueous KPS initiator solution was started. The delayfeed rate for the reaction was as follows:

about 4.6 ml/min for the first hour; and

about 5.5 ml/min for the remaining monomers.

In a separate container, 3.2 g of hydroxyethyl cellulose (HEC) and 88.0g of DI water were mixed together. This HEC solution was mixed with thelast 15% of the monomer pre-emulsion. The following additionalsurfactants were also added into HEC solution at this stage:

(i) branched alcohol ethoxy phosphate surfactant or 6.0 gpolyoxyethylene tridecyl ether phosphate (25% active) (ii) ammonium saltof phosphate ester surfactant (100% active) 3.0 g

Suitable phosphate ester surfactants include but are not limited totristyrylphenol ethoxylate phosphate ester. The tristyrylphenolethoxylate phosphate ester (100% solids) was diluted with DI water in20% and neutralized with ammonium hydroxide to the pH value of 9.5-10.0before use. 17 g of 20% tristyrylphenol ethoxylate phosphate ester(neutralized) was used in the above example. The addition of extrasurfactants together with HEC solution was surprisingly effective inpreventing the gel formation from the grafting.

About 15-30 minutes after the feed, the batch became viscous and thenreturned to a workable viscosity again after holding the temperature at82° C. for an additional 30-60 minutes. The batch was cooled down to65-68° C., and chasers (t-butyl hydroperoxide and sodium formaldehydesulfoxylate) and ammonium hydroxide were added with agitation. Theproperties of the produced latex were shown in the following table.

MFFT Particle Particle size Mechanic Solids pH (° C.) size(mV) (mV)Stability After pH Rhopoint Before HEC After HEC 10,000 rpm filtrationmeter WP addition addition 43.0% 8.0 12.8 145 nm 543 nm >30 min.

As discussed above, this HEC grafted acrylic latex sample showedexcellent water resistance and was water permeable. Water permeabilityresults are shown in the following table. This property allowsapplications in areas outside the paint industry, e.g., the HEC graftedacrylic latex may be suitable as a material for contact lenses.

Specific Permeability⁽³⁾ Sample ID mg/cm² · mm · 24 hr Control latexwithout HEC⁽¹⁾ 0.38 HEC grafted Latex⁽²⁾ 1.01 ⁽¹⁾Control acrylic latexsample without any HEC during the reaction. ⁽²⁾HEC grafted acrylic latexsample from example 1. HEC is about 0.5% vs. total weight of monomers.⁽³⁾See Material and Methods Section

Example 2

To the same reactor setup as described in Example 1, 460 g of DI waterand 0.65 g of sodium bicarbonate were added. The reactor was heated to78° C. and agitated at 160 RPM. The following ingredients were mixed toform monomer pre-emulsion.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 290.0 g Butyl acrylate (BA) monomer309.0 g Methacrylic acid (MAA) monomer  4.4 g Methacrylamide (MAM)monomer  2.6 Styrene monomer  12.9 g N-(2-methacryloyloxyethyl)ethyleneurea  26.3 g DI water 226.0 g Sodium dioctyl sulfosuccinate surfactant 6.0 g Blend of anionic and nonionic surfactants  3.0 g

A suitable example of a blend of anionic and nonionic surfactants can beCytec XSM 1110 (50% active). After the monomer pre-emulsion formed, 2.9g of ammonium hydroxide (28%) was added to the monomer emulsion for a pHof 6.2.

About 41.0 g of this monomer emulsion and about 10 ml of 12.6% aqueouspotassium persulfate (KPS) initiator solution were charged into thereactor for seed. After 20 minutes of heating at 79° C., seed particlesformed, and the monomer pre-emulsion was fed into the reactor at thefollowing rate:

about 4.6 ml/min. for the first hour; and

about 5.5 ml/min. for the rest of the monomer emulsion.

About 25 ml of 4% KPS initiator in DI water was also co-fed with themonomer emulsion.

When about 8-10% of total monomer pre-emulsion was remaining, 83 g of3.9% HEC solution in DI water together with 5.2 g of RHODAFAC® RS610/A25and 5.5 g of AEROSOL® 22 surfactants were added to the 8-10% remainingmonomer emulsion to complete the delay feed in 40-60 minutes. The totalswere fed completely in about 3 hours and the latex was held at about 82°C. for additional 50-60 minutes and then cooled down to 65° C. Chasersand ammonium hydroxide were added. The properties of the produced latexare shown in the table below.

Particles size (mV) Particle size (mV) Solids MFFT (° C.) pH before HECgrafting after HEC grafting 43% 13 8.0 191 nm 239 nm

The paint sample made with this latex showed water sensitivity due tothe absence of the monomer combination methacrylamide/DAAM/styrene. Thegrafting was not as effective as in Examples 1 and 4 due to insufficientmonomer emulsion (about 8%) when HEC was added. The final averageparticle size (mV) after the HEC grafting reaction was smaller than thatof the typical HEC grafted samples which ranges from about 300 nm toabout 900 nm.

Example 3

To the same reactor setup as described in Example 1, 534 g of DI waterwas added. The reactor was heated to 79° C. and agitated at 180 RPM. Toa 2 liter Erlenmeyer flask, the following ingredients were mixedtogether and agitated for at least 20 minutes to form a stable monomerpre-emulsion.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 300.6 g Butyl acrylate (BA) monomer374.4 g Methacrylic acid (MAA) monomer  6.2 g Diacetone acrylamide(DAAM)  3.4 g Styrene monomer  40.0 g N-(2-methacryloyloxyethyl)ethylene urea  17.5 g Wet adhesion monomer (50%) 2-Ethylhexyl acrylate(2-EHA)  23.2 g DI water 264.0 g Sodium dioctyl sulfosuccinatesurfactant  2.6 g Tetrasodium N-(1,2-dicarboxyethyl)-N-octadecyl  4.6 gSulfosuccinamate surfactant (35% active) Ammonium salt of phosphateester surfactant  8.4 g

After the monomer pre-emulsion formed, 1.7 g of ammonium hydroxide (28%)was added to the monomer emulsion for a pH of 6.5.

About 50.4 g of this monomer emulsion and about 15 ml of 10.6% aqueouspotassium persulfate (KPS) initiator solution were charged into thereactor for seeding. After 20 minutes of heating at 79° C., seedparticles were formed, and the monomer pre-emulsion was delay fed intothe reactor at the following rates:

about 6.5 ml/min. for the first hour; and

about 7.4 ml/min. for the rest of the monomer emulsion.

About 68 ml of 2.4% KPS initiator in DI water was also co-fed with themonomer emulsion.

When about 10-14% of total monomer pre-emulsion was remaining, 99 g of3.9% HEC solution in DI water together with 7.8 g of polyoxyethylenetridecyl ether phosphate, ammonium salt and 20.4 g of ammonium salt ofphosphate ester surfactant (neutralized at 20%) were added into theremaining monomer pre-emulsion and delay fed into the reactor togetherwith KPS solution. The latex became very viscous near the end of the HECfeed but the viscosity would eventually drop after one hour holding. Theagitation RPM was raised to ensure proper mixing. The total feed timefor the monomers was about 3 hours and the batch was then held at about82° C. for additional 60 minutes. After the hold, the batch was cooleddown to 65° C. and the chasers and ammonium hydroxide were added forreducing residual monomer and pH control. The properties of the producedlatex are in following table.

Particles size Particle size (mV) (mV) before HEC after HEC Solids MFFT(° C.) pH grafting η (cP) grafting 41.2% 6.0 8.8 177 nm 410 639 nm

Comparative Experiment A

The water sensitivity tests were performed on the latexes of the paintsamples for Examples 1-3 following the procedure in the Material andMethods section. The results are summarized in the following table.

Film Drying time 4 hrs. 5 hrs. 6.5 hrs. 24 hrs. 7 days Water wettingtime 5 min. 5/10 min. 5/10/25 min. 10 min. 25 min. Water sensitivity 4⁺5/4⁻ 5⁺/5/4 Not Not (1-5) scratchable scratchable Example 1 5⁺ 5+DAAM/MAM combo Water sensitivity 0 Not available Not available Poor filmPoor water (1-5 ) strength sensitivity Example 2 1⁺ 2 without DAAM Watersensitivity 1⁻ 1/1⁻ 1⁺/1/0-1 Poor film Scratchable (1-5) strength 3Example 3 2 without MAM

Example 4

HEC Added with 31% Monomer Pre-Emulsion

To the same reactor setup as described in Example 1, 425.0 g ofdeionized (DI) water was added and heated to 79° C.

To an Erlenmeyer flask, the following ingredients were added and stirredto form a stable monomer pre-emulsion.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 259.3 g Butyl acrylate (BA) monomer322.5 g Methacrylic acid (MAA) monomer  5.2 g Methacrylamide (MAM)monomer  2.5 g Diacetone acrylamide (DAAM) monomer  2.9 g Styrenemonomer  29.8 g N-(2-methacryloyloxyethyl)ethylene urea  25.9 g Wetadhesion monomer DI water 210.0 g Sodium dioctyl sulfosuccinatesurfactant  2.1 g (AEROSOL ® OT-75) (75% active) TetrasodiumN-(1,2-dicarboxyethyl)-N-octadecyl  5.2 g Sulfosuccinamate surfactant(AEROSOL ® 22) (35%) Ammonium salt of phosphate ester surfactant (100%) 0.6 gAbout 1.8 g of ammonium hydroxide (28%) was also added for pHadjustment.

About 15 ml of 8.6% potassium persulfate (KPS) aqueous initiatorsolution and about 40.0 g of the monomer pre-emulsion were charged tothe reactor at 79° C. to form seed particles. After about 20 minute at79° C. with agitation, the delay feed of monomer pre-emulsion, togetherwith 30 ml of 4.1% aqueous KPS initiator solution was started. The delayfeed rate for the reaction was as follows:

about 4.6 ml/min for the first hour; and

about 5.5 ml/min for the remaining monomers.

In a separate container, 3.2 g of hydroxyethyl cellulose (HEC) and 91.0g of DI water were mixed together. This HEC solution (3.5%) andadditional surfactants were mixed with the last 31% of monomerpre-emulsion and feeding was continued. When the monomer pre-emulsionwas 80-85% fed, the remaining pre-emulsion (20%-15%) was mixed with thefollowing ingredients and the feed was continued.

Branched alcohol ethoxy phosphate surfactant (25% active) 6.0 g Ammoniumsalt of phosphate ester surfactant (100% active) 3.4 g

About 20 minutes after all the ingredients were fed, the latex becameviscous, and then reduced to normal viscosity after 45-60 minutesholding the temperature at 82° C. The batch was cooled down to 66° C.,and chasers (t-BHP and SFS (sodium formaldehyde sulfoxylate)) andammonium hydroxide were added. The properties of the produced latex wereshown in the table below.

MFFT Particle size Particle size Mechanic Solids (° C.) (mV) (mV)Stability After pH Rhopoint Before HEC After HEC 10,000 filtration pHmeter WP addition addition rpm 43.6% 8.0 10.1 162 nm 548 nm >30 min.

The particle size of this batch showed a bimodal distribution for thesample taken at 45 minutes hold, and uni-modal distribution after 100minutes hold.

Example 5

To the same reactor setup as described in Example 1, 420 g of DI waterwas added with nitrogen sweep and agitation at 170 RPM. The followingingredients were mixed to form a monomer pre-emulsion.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 265.3 g Butyl acrylate (BA) monomer306.6 g Methacrylic acid (MAA) monomer  5.4 g Methacrylamide (MAM)monomer  2.6 g Diacetone acrylamide (DAAM) monomer  2.9 g2-Ethylhexylacrylate (2-EHA) monomer  25.6 gN-(2-methacryloyloxyethyl)ethylene urea wet adhesion monomer  25.6 gN-methylol methacrylamide monomer  7.4 g DI water 220.0 g Sodium dioctylsulfosuccinate surfactant  2.3 g TetrasodiumN-(1,2-dicarboxyethyl)-N-octadecyl  5.4 g Sulfosuccinamate surfactant(50%)After the monomer pre-emulsion is formed, about 1.5 g of ammoniumhydroxide (28%) was added to the monomer emulsion for pH adjustment.

About 41.0 g of this monomer pre-emulsion and about 10 ml of 12.6%potassium persulfate (KPS) initiator solution were charged into thereactor forming seed particles. After 20 minutes heating at 79° C., themonomer pre-emulsion was delay fed into the reactor at the followingrate:

about 4.6 ml/min for the first hour; and

about 5.5 ml/min. for the rest of the monomer emulsion.

About 30 ml of 4.1% potassium persulfate (KPS) initiator in DI water wasalso co-fed with the monomer pre-emulsion.

When about 3% of total monomer pre-emulsion was remaining, 94.0 g of3.9% pre-dissolved HEC water solution, together with 6.0 g ofpolyoxyethylene tridecyl ether phosphate, ammonium salt and 3.3 g ofammonium salt of phosphate ester (100%) surfactants were added to the 3%remaining monomer emulsion to complete the delay feed in about 50minutes. The batch was held at 82° C. for additional 50-60 minutes andthen cooled down to 65° C. Chasers and ammonium hydroxide were added.The properties of the produced latex were shown in the table below.

Particles size (mV) Particle size (mV) Solids MFFT (° C.) pH before HECgrafting after HEC grafting 43.2% 6.8 8.0 198 nm 235 nm

Example 6

To the same reactor setup as described in Example 1, 435 g of DI waterwas added with nitrogen sweep and agitation at 170 RPM. The followingingredients were mixed to form a monomer pre-emulsion.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 278.7 g Butyl acrylate (BA) monomer252.7 g Methacrylic acid (MAA) monomer  5.3 g Methacrylamide (MAM)monomer  5.2 g Diacetone acrylamide (DAAM) monomer  2.6 g2-ethylhexylacrylate (2-EHA) monomer  84.3 gN-(2-methacryloyloxyethyl)ethylene urea  11.7 g wet adhesion monomer(50% solution in water) N-Methylol methacrylamide monomer (N-MMAA)  7.8g DI water 220.0 g Sodium dioctyl sulfosuccinate surfactant  2.0 gTetrasodium N-(1,2-dicarboxyethyl)-N-octadecyl  5.2 g Sulfosuccinamatesurfactant (50%) Ammonium salt of phosphate ester surfactant  0.4 g

Suitable phosphate ester surfactants include but are not limited totristyrylphenol ethoxylate phosphate ester, which may be diluted with DIwater. After the monomer pre-emulsion is formed, about 1.8 g of ammoniumhydroxide (28%) was added to the monomers for pH adjustment.

About 40.0 g of above monomer pre-emulsion and 10 ml of 13.0% potassiumpersulfate (KPS) initiator solution were charged into the reactor forseed particles. After 20 minutes heating at 79° C., and the monomerpre-emulsion was delay fed into the reactor at the following rate:

about 4.6 ml/min. for the first hour; and

about 5.5 ml/min. for the rest of the monomer emulsion.

About 30 ml of 4.1% potassium persulfate (KPS) in DI water was alsoco-fed with the monomer pre-emulsion.

When about 36% of total monomer pre-emulsion remained, 94.0 g of 3.9%pre-dissolved HEC water solution, together with 6.0 g of polyoxyethylenetridecyl ether phosphate, ammonium salt and 3.3 g of ammonium salt ofphosphate ester (100%) surfactants were added to the 36% remainingmonomer emulsion to complete the delay feed in about 40 minutes. Thebatch was held at 82° C. for additional 60 minutes and then cooled downto 65° C. Chasers and ammonium hydroxide were added. The properties ofthe produced latex were shown in the table below.

Particles size (mV) Particle size (mV) Solids MFFT (° C.) pH before HECgrafting after HEC grafting 42.4% 4.3 8.0 170 nm 255 nm

The final average particle was smaller when using 2-ethylhexylacrylate(2-EHA) monomer and N-methylol methacrylamide monomer (VISIOMER® N-MMAA)in the acrylic composition, even when HEC was mixed with higherconcentration of monomer pre-emulsion. However, when 2-EHA was used inthe acrylic monomer compositions, the particle size distribution of thegrafting reaction did not go through a bimodal distribution stage,indicating more resistance to coagulation/gelling. The samples taken atdifferent holding time after the HEC addition all showed unimodalparticle distributions.

Example 7

To a three-neck 5 L reactor equipped with a digital agitator andtemperature controller was added 445 grams of DI water. The reactor washeated to 82.0° C. with N₂ sweep and agitated at a speed of 170-185 RPM.Then a monomer emulsion (41.0 g) of the following composition and KPS(1.35 g) were both charged to the reactor to form latex seeds. After theseed particles were formed in about 20 minutes, the remaining monomeremulsion was fed into the reactor at 5.0 ml/minute. An amount of KPSinitiator aqueous solution (30 ml, at 4.1% concentration by weight) wasco-fed with the remaining monomer emulsion during the 3 hours feed time.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 254.0 g Butyl acrylate (BA) monomer311.0 g Methacrylic acid (MAA) monomer  4.7 g Methacrylamide (MAM)monomer  1.8 g Diacetone acrylamide (DAAM) monomer  4.5 g Styrene  38.6g N-(2-Methacryloyloxyethyl)Ethylene Urea  26.5 g 25% Solution inMethylmethacrylate DI water 215.0 g Sodium dioctyl sulfosuccinatesurfactant (75%)  2.2 g Tetrasodium N-(1,2-dicarboxyethyl)-N-octadecyl 5.2 g Sulfosuccinamate surfactant Ammonium hydroxide (28%)  1.8 g

Into a separate container equipped with a magnetic stirring bar,hydroxyethyl cellulose (HEC) (3.2 grams) was dissolved in DI water (88g) for a subsequent use.

After 80%-90% of the monomer emulsion was fed, the above solution of HECin DI water (88.0 g), phosphate ester surfactant (20%, 16.0 g), andpolyoxyethylene tridecyl ether phosphate, ammonium salt (6.0 g) fromRhodia were properly mixed into the remaining monomer emulsion. Theresulting monomer emulsion with HEC was fed into the reactor which washeld at 82° C. for about another hour to complete the polymerization.The HEC grafting reaction initially increased the viscosity of the batchwhich would become normal again after ½ hour of agitation during thehold period.

The redox chasers t-BHP and SFS were added into the reactor after thebatch was cooled down to about 65° C. for residual monomer reduction.The latex in the reactor was neutralized with ammonium hydroxide aqueoussolution until its pH was about 8.3.

Properties of the latex of Example 7 Mechanical Film gloss pH Solids %Particle size MFFT Stability (60°) 8.3 41.6% 430 nm 13.5° C. Pass 83Mechanical stability test was conducted by a high speed mixer with arotational speed range of 10,000-18,000 RPM, e.g., bench top mixer modelNo. 936 made by Hamilton Beach. A mass of about 250 g-300 g of emulsionlatex is placed into a stainless cup and agitated at about 12,000 RPMfor 30 minutes. Defoamer agent can be added if the latex becomes foamydue to mixing. If the latex survives the 30 minutes mixing withoutgelation, the latex emulsion passes the mechanical stability test.

Example 8

Similar to the setup as described in Example 7, DI water (445.0 g) andsodium dodecylbenzene sulfonate (2.0 g) were charged into a reactorwhich was then heated to 82.0° C. In a separate container, HEC (3.2 g)was dissolved in DI water (88.0 g) in 20-30 minutes with agitation untilthe solution turned clear.

A monomer emulsion was prepared with the following components. An amountof this monomer emulsion (about 40.0 g) and KPS (1.3 g) were chargedinto the reactor to form the latex seed particles. The remaining monomeremulsion was then co-fed into the reactor with a KPS solution (30 ml,3.4% concentration by weight) in about 2.5 hours. The HEC solutionprepared above was added to the monomer emulsion remained and feedingwas continued. The batch was then held at 82° C. for another 60 minutesto complete the polymerization.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer  270 g Butyl acrylate (BA) monomer 310 g Methacrylic acid (MAA) monomer  4.8 g Methacrylamide (MAM)monomer  2.5 g Diacetone acrylamide (DAAM) monomer  2.9 g Styrene 29.5 gN-(2-Methacryloyloxyethyl)Ethylene Urea 25.7 g 25% Solution inMethylmethacrylate Ammonium hydroxide (28%)  1.9 g DI water  220 gSodium dioctyl sulfosuccinate (75%)  2.2 g TetrasodiumN-((1,2-dicarboxyethyl)-N-octadecyl  3.8 g sulfosuccinamate (35%)Phosphate ester surfactant (20%)  5.0 g

The solids at different time intervals were taken from the reactor andlatex particle sizes analyzed. The results are summarized in thefollowing table.

20 min Sample before Sample at the ID seeds HEC addition end of reactionSolids % 5% 39.6% 43.0% Particle size (nm) 36 nm 122 nm 542 nm

The test results for latex sample are shown the table below.

Properties of the latex of Example 8 pH Solids Particle size MFFT(° C.)Mechanical Stability (30 min.) 8.2 43.0% 542 nm 14.0 Pass

Example 9

Similar to the setup as described in Example 7, DI water (445 g) wasadded and the reactor heated to about 82.0° C. The following componentswere mixed to form a stable monomer emulsion by agitation.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 251.0 g Butyl acrylate (BA) monomer308.0 g Methacrylic acid (MAA) monomer 5.4 g Methacrylamide (MAM)monomer 3.2 g Diacetone acrylamide (DAAM) monomer 0.7 g Styrene 51.5 gN-(2-Methacryloyloxyethyl)Ethylene Urea 25.8 g 25% Solution inMethylmethacrylate Ammonium hydroxide (28%) 1.9 g Sodium dioctylsulfosuccinate surfactant (75%) 2.2 g TetrasodiumN-(1,2-dicarboxyethyl)-N-octadecyl 5.3 g sulfosuccinamate surfactantPhosphate ester surfactant 16.0 g Polyoxyethylene tridecyl etherphosphate, ammonium 6.0 g salt (25%)

To the reactor, ammonium hydroxide (28%, 2.8 g) was added to bring thepH from about 6.0 to 8.3. Other additives such as biocides andstabilizers can also be added to the final emulsion polymer latex. Thefollowing table contains the results from the latex sample:

Properties of the latex of Example 9 Stability MFFT Film Gloss pH Solids(30 min.) Particle size (° C.) (60°) 8.3 43.0% Pass 660 nm 14.0 81 MFFTis the minimum film forming temperature. Film gloss was measured by aBYK-Gardner gloss meter.

Example 10

To a similar reactor setup described as in the Example 7, DI water (420g) and sodium dodecylbenzene sulfonate (1.5 g) were added. 42 g of thefollowing monomer emulsion and KPS (1.3 g) were added to the reactor at82° C. to form the seed particles. The remaining monomer emulsion wasfed into the same reactor at a rate of 5.0 ml/minute. In a separatecontainer, HEC (3.30 g) was dissolved in DI water (91 g) for subsequentuse.

The following ingredients were mixed together by agitation until astable monomer emulsion was formed.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 265.3 g Butyl acrylate (BA) monomer307.4 g Methacrylic acid (MAA) monomer 5.5 g Methacrylamide (MAM)monomer 2.5 g Diacetone acrylamide (DAAM) monomer 2.9 g Styrene 12.8 gN-(2-Methacryloyloxyethyl)Ethylene Urea 25.6 g 25% Solution inMethylmethacrylate 2-Ethylhexylacrylate (2-EHA) monomer 19.2 g DI water220 g Sodium dioctyl sulfosuccinate surfactant (75%) 2.1 g TetrasodiumN-(1,2-dicarboxyethyl)-N-oetadecyl 5.1 g sulfosuccinamateTristyrylphenol ethoxylate phosphate ester (20% active) 1.0 g Ammoniumhydroxide (28%) 1.6 g

After about 85% of the monomer emulsion had been fed into the reactor, aHEC solution (94.3 g, at a concentration of 3.4% by weight) was addedinto the remaining monomer emulsion together with tristyrylphenolethoxylate phosphate ester (18.5 g) and Polyoxyethylene tridecyl etherphosphate (5.8 g) to complete the feed as described in Example 7.

After a one hour hold at 82° C., the batch was cooled down to about 60°C. Redox chasers (t-BHP/SFS) and ammonium hydroxide were added forresidual monomer reduction. The table below shows the properties of theobtained latex.

Properties of the latex of Example 10 Mechanical % Solids MFFT (° C.)Particle size pH Stability (30 min.) 43.7% 8.5 ° C. 178 nm 8.1 >30 min.Pass

Comparative Experiment B

Paint samples substantially free of ADH were made from the latexes fromExamples 7-10 and commercial latex free of MAM and DAAM using thefollowing procedure. A grind was made from following components insection A in a stainless container. The components were mixed byagitation at a very high RPM for at least 15 minutes before beingswitched to a lower RPM. The letdown was made from the ingredients insection B.

SECTION A (Grind) Water 35.0 Preservative 2.0 Mildewcide 2.5 AcrylicPolymer Dispersant 1 9.0 Ethoxylated Nonionic Surfactant 1 (80% inwater) 3.0 TiO2 Pigment 200.0 Defoamer 1 0.75 Additional DI Water 76.22-Amino-2-methyl-1-propanol (95% in water) 1.5 co-dispersant Non-ionicsurfactant 2 (80% in water) 5.0 Water 20.0

SECTION B (Letdown) HEUR Rheology Modifier 12.0 Latex binders 470.0Acrylic Polymer Open Time Extender (25% in water) 10.0 PolyurethaneResin (35% in water) 30.0 Coalescent 15.0 Suppressor HEA 4.5Hydrophobically modified polyether rheology modifier 17.0 (18% in water)Modified paraffin wax emulsion (38% in water) 12.0 Fluorosurfactant 2.0Propylene Glycol 12.0 DI Water 54.2

The data on scrub resistance, block resistance, and other relatedproperties were generated from the paint samples made from latex samples7-10 for comparison purpose. The evaluation methods used are standardASTM D4946-89, ASTM 2486-06, and ASTM D7190-10 (American Standard TestMethod) procedures described in the material and methods section. Thereference methods can be found in the ASTM website(http://www.astm.org/). The table below shows the scrub resistance,block resistance, water sensitivity and water stain resistance resultsfor the paint samples made from latexes of Examples 7-10. A controlsample which contains no crosslinking monomer is included forcomparison.

MAM: Block Water Water DAAM Scrub resis- sensitivity stain ID (weightratio) resistance tance (2 min.) resistance Example 7 1:2.5 1430 5 Pass4.5 5 Example 8 1:1.16 1300 5 Pass 4.5 5 Example 9 1:0.22 1043 5 Pass4.5 5 Example 10 1:1.16 1296 5 Pass 4.8 5 Control Sample N/A 516 5 Pass1.5 2

Example 11

To a similar reactor setup as described in Example 7, DI water (681.0 g)and sodium dodecylbenzene sulfonate (8.5 g) were added and the mixturewas heated to a temperature of 81° C. with N₂ sweep. The followingcomponents were added into an Erlenmeyer flask with agitation until astable monomer emulsion was formed. To the reactor, an amount of stage Imonomer emulsion (70.0 g) together with KPS (2.1 g) was charged. Theagitation was maintained at a speed of 190 RPM for about 20 minutes.After the emulsion seed was formed, the rest of the stage I monomeremulsion was fed into the reactor with a KPS solution (27 ml, 0.4% byweight) in about 1 hour and 5 minutes.

Stage I monomer pre-emulsion. (Tg is estimated at about 41.0° C.)

Methyl methacrylate (MMA) monomer 284.0 g Butyl acrylate (BA) monomer118.4 g Acrylic acid (AA) 4.0 g 1,4-Butanediol diacrylate (SR-213) 1.6 gDI water 255.6 g Sodium dodecylbenzene sulfonate (RHODACAL ® DS-4) std19.9 g (23% active) Sodium lauryl sulfate (30% active) 10.5 g Ammoniumhydroxide (28%) 0.6 g

The Stage II monomer emulsion has the following composition. It wasprepared in a similar procedure as disclosed for the stage I monomeremulsion. It was then fed into the reactor after the stage I monomeremulsion feed was finished. The total feed of stage II monomer emulsionand a KPS solution (83 ml, 0.4% by weight) was completed in about 2hours and 10 minutes. The batch was then held at 82° C. for another50-60 minutes and cooled down to about 65° C. The redox chasers t-BHP(0.04%) and FF6 (0.03%) were added to the batch for the residual monomercontrol. The pH value of the latex batch was adjusted with appropriateamounts of ammonium hydroxide. Other preservatives and stabilizers canalso be added to the latex batch for improving the shelf life andperformances.

Stage II monomer pre-emulsion. The estimated Tg is about 13.9° C.

Methyl methacrylate (MMA) monomer 330.0 g Butyl acrylate (BA) monomer281.0 g Methacrylic acid (MAA) monomer 10.2 g Methacrylamide (MAM)monomer 1.2 g Diacetone acrylamide (DAAM) monomer 1.6 gN-(2-Methacryloyloxyethyl)Ethylene Urea 50% Solution In 21.3 g Water(VISIOMER ® 6852-O) Vinyl neodecanoate (VEOVA ™ 10) 460.1 g DI water582.2 g Sodium lauryl sulfate (30%) 37.0 g Sodium vinyl sulfonate (SVS)3.1 g Sulfosuccinate surfactant (50%) 10.0 g Ammonium salt of phosphateester surfactant (20%) 30.5 g Ammonium hydroxide 1.2 g

The latex batch has the following parameters in following table and wasmade into paint using the similar procedures disclosed in above example.

Total residual Solids Particle Mechanic monomers by % size MFFTStability pH Mw GC method 45.9% 123 nm 8.0 ° C. >30 min. pass 8.2110,000 0.2%

Example 12

This experiment was run with the same procedures and compositiondescribed in example 11 as a control. However, it contains only DAAM(1.6 g) and no MAM (0.0%) in its second stage monomer emulsion. Theblock resistance test of the paint sample made from this latex generatedpoor block resistance result. It failed the block resistance test at120° F. for 24 hours.

The data in the following table was measured on the latex sample. Thesmaller particle size is due to the higher surfactant level, sodiumdodecylbenzene sulfonate, in the initial water phase.

Solids % Particle size MFFT Stability pH Mw 44.9% 72 nm 8.0° C. >30 min.pass 8.3 78,000

Example 13

This experiment was run with the same procedures and composition asdescribed in Example 11. However, it contains only 1.2 g of MAM andwithout any DAAM (0.0%) in its second stage monomer emulsion. The blockresistance test of the paint sample made from this latex generated poorblock resistance result under the ASTM method conditions of 120° F. for24 hours. The smaller particle size is due to the higher surfactantlevel in its water phase. Table 17 shows the test results of the latexsample.

Solids % Particle size MFFT Mechanic stability pH Mw 44.3% 77 nm 7.0°C. >30 min. pass 8.3 88,400

Example 14

This example was run with the same procedure as described in example 11except that the there is no DAAM in its composition and that BA monomerwas replaced by 2-EHA monomer. The sodium dodecylbenzene sulfonatesurfactant is also higher in the initial water phase. Therefore theaverage particle size (mV) of this batch is also smaller. A personskilled in the arts can easily adjust the surfactant levels andcombinations to achieve the desired particle size distributions.

Stage I monomer emulsion. The estimated Tg for stage I polymer is about41.0° C.

Methyl methacrylate (MMA) monomer 284.0 g Butyl acrylate (BA) monomer118.4 g Acrylic acid (AA) 4.0 g 1,4-Butanediol diacrylate 1.6 g DI water255.6 g Sodium dodecylbenzene sulfonate (23% active) 19.9 g Sodiumlauryl sulfate (30% active) 10.5 g Ammonium hydroxide (28%) 0.6 g

Stage II monomer emulsion. The estimated Tg for stage II is about −1.5°C.

Methyl methacrylate (MMA) monomer 330.0 g Methacrylic acid (MAA) monomer10.2 g Methacrylamide (MAM) monomer 1.2 gN-(2-Methacryloyloxyethyl)Ethylene Urea (50% in water) 21.3 g2-Ethylhexyl acrylate (2-EHA) 281.0 g Vinyl neodecanoate 460.1 g DIwater 582.2 g Sodium lauryl sulfate (30%) 37.0 g Sodium vinyl sulfonate(SVS) 3.1 g Sulfosuccinate surfactant (50%) 10.0 g Ammonium salt ofphosphate ester surfactant (20%) 30.5 g Ammonium hydroxide (28%) 1.2 gThe latex has the following characteristic results as shown in the tablebelow.

Solids Particle size MFFT Mechanic stability pH Mw 44.8% 75 nm 5.6°C. >30 min. 8.2 103,000

Comparative Experiment C

The following table shows the results of block resistance for paintsamples made from the latex of Examples 11-14 for comparison.

ID Example 11 Example 12 Example 13 Example 14 MAM:DAAM 1:1.33 N/A N/AN/A (weight ratio) Block 4 (pass) 2 (fail) 3 (fail) 3 (fail) ResistanceTinted color Hamilton blue Hamilton blue Hamilton blue Hamilton blue

Example 15

To a similar reactor set up to Example 7 DI water (450.0 g), sodiumC₁₄-C₁₆ olefin sulfonate (40% active, 1.5 g), and 1.0 g of NaHCO₃ wereadded and heated to 82.0° C. with N₂ sweep and agitation. The monomeremulsion was formed in a separate Erlenmeyer flask using the ingredientslisted below.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 430.0 g Butyl acrylate (BA) monomer435.0 g Methacrylic acid (MAA) monomer  9.0 g Methacrylamide (MAM)monomer  5.5 g Diacetone acrylamide (DAAM) monomer  8.3 gN-(2-methacryloyloxyethyl)ethylene urea  19.2 g wet adhesion monomer(50%) Ammonium hydroxide (28%)  1.0 g Sodium C₁₄-C₁₆ olefin sulfonate(40%)  5.8 g Polyoxyethylene tridecyl ether phosphate, ammonium salt(25%)  16.0 g tristyrylphenol ethoxylate phosphate ester (20%)  18.5 gDI water 360.0 g

Into a separate container, HEC (0.9 g) was dissolved in DI water (40.0g) which will be added later with the remaining 25% monomer emulsionduring the feed.

Following surfactants were mixed with HEC solution before addition tothe feed, which would prevent the coagulation/gelling.

Polyoxyethylene Tridecyl Ether Phosphate, Ammonium Salt

(RHODAFAC ® RS 610/A25) (25%) 10.6 g POLYSTEP ® TSP-16 PE30 16.7 g

An amount of monomer emulsion (60.0 g) and KPS (1.75 g) were charged tothe reactor to form latex seed particles. The remaining monomer emulsionand KPS solution (90 ml, 1.1% by weight) were co-fed during a 3 hoursperiod and then held for another hour. The t-BHP/FF6 pair (1.0 gt-BHP/0.85 g FF6) was used at the end of the reaction for residualmonomer control, as well as the ammonium hydroxide to adjust the pHvalue to 8.2 and also other necessary preservatives such as Polycide 428by example. The latex was filtered through a 140 mesh size screen filterand tested, and has the following parameters for reference:

MAM:DAAM Solid (weight ratio) Particle size MFFT Film Gloss pH 46.6%1:1.51 141 nm 10.6° C. 72 (60°) 8.2

Example 16

Using the same procedure and setup as disclosed in Example 15, 450.0 gof DI water, 1.5 g of sodium C₁₄-C₁₆ olefin sulfonate (40% active) and1.0 g of NaHCO₃ were charged into the reactor and the mixture heated to82.0° C.

The following monomer emulsion was delay fed into the reactor with KPSsolution. When there was about 20% monomer emulsion remaining, 40.0 g ofpre dissolved HEC solution was added to the monomer emulsion and thefeed was continued until finished. After a one-hour hold, the batch wascool down to 65° C., redox pair, ammonium hydroxide, and otherpreservatives were added. Extra surfactant can also be added at thisstage to improve the mechanical stability.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 430.0 g Butyl acrylate (BA) monomer424.0 g Methacrylic acid (MAA) monomer  8.2 g Methacrylamide (MAM)monomer  2.8 g Diacetone acrylamide (DAAM) monomer  12.2 g Styrene  27.1g N-(2-methacryloyloxyethyl)ethylene urea  18.2 g Wet adhesion monomer(50% in water) Ammonium hydroxide (28%)  2.0 g Sodium C₁₄-C₁₆ olefinsulfonate (40%)  5.8 g Polyoxyethylene tridecyl ether phosphate,ammonium salt (25%)  16.0 g Ammonium salt of phosphate ester surfactant(20%)  18.5 g DI water 360.0 g

The following HEC solution was added with 20% remaining monomer emulsionand delay fed into the reactor.

Hydroxyethyl cellulose (HEC)  0.9 g DI water 39.1 g Polyoxyethylenetridecyl ether phosphate, ammonium salt (25%) 10.6 g Ammonium salt ofphosphate ester surfactant (20%) 16.7 gLatex Parameters:

MAM:DAAM Particle Mechanical Solid (weight ratio) size MFFT stability pH47.6% 1:4.36 126 nm 13° C. Pass 8.2The mechanical stability is described in the earlier section and pass israted when there is no gel formation after 30 minutes stirring at 12,000RPM.

Paint examples A, B and C were made according to the following procedureand the paint samples are tested for their mechanical and physicalproperties.

Comparative Experiment D Control Paint Example I

A standard paint was prepared as follows. Formulation of a control paintexample I uses an all acrylic latex composition without crosslinkingfunctionality. All weights are in grams.

Grind: Propylene Glycol 10.8 Water 104.5 Biocide 1 1.5 Antimicrobial 11.9 Acrylic polymer dispersant 2 7.7 Potassium carbonate 1.7 Titaniumdioxide pigment 232.1 Extender Pigment 1 37.1 Extender Pigment 2 25.5Extender Pigment 3 34.8 Extender Pigment 4 8.5 Extender Pigment 5 8.5Defoamer 2 0.7

Letdown: Phosphate Ester Surfactant, Ammonium Salt (25%) 1.5 NonionicSurfactant 3 3.5 Nonionic surfactant 4 0.8 Anionic Surfactant 1 (60%)1.5 Coalescent 13.2 All Acrylic Latex without Crosslinking Functionality321.1 Polyurethane resin 19.3 Hydrophobically modified polyetherrheology modifier 18.6 Hydrophobically modified polyethylene oxideurethane 7.0 Defoamer 2 2.3 Defoamer 3 2.3 Water 33.1The paint has a viscosity of 99 KU and 1.862 ICI.

Paint Example with Inventive Latex from Example 15

A paint composition using latex of Example 15 is prepared in the samemanner as described for Control Paint Example I except that 351.4 g ofExample 15 latex is used instead of 321.1 g of the control acrylic latexand 2.8 g of water is used in the letdown instead of 33.1 g of water.Also, 20 g of hydrophobically modified polyether rheology modifier isused instead of 18.6, and the amount of hydrophobically modifiedpolyethylene oxide urethane is decreased by 0.5 g (to 6.5 g) to yield apaint composition with a viscosity of 95 KU and 1.717 ICI.

Paint Example (a) with Inventive Latex from Example 16

A paint composition using the latex of Example 16 was prepared in thesame manner as described for control paint Example I except that 351.4 gExample 16 latex was used instead of 321.1 g control acrylic latex and2.8 g water was used in the letdown instead of 33.1 g water. Also, 15 gof hydrophobically modified polyether rheology modifier was used insteadof 18.6 g, and the hydrophobically modified polyethylene oxide urethaneamount was decreased by 3.5 g (to 3.5 g) to yield a paint with aviscosity of 104 KU and 1.679 ICI.

The paint samples as described above were tested for their physical andmechanical properties and the results were entered into the table below.Effect of crosslinking on the physical and mechanical properties

Block resistance MAM:DAAM Scrub Water stain Water sensitivity (24 hrs atID (weight ratio) (Cycles) resistance (5 min.) 120° F.) Control PaintExample I N/A 1050 2 3 4 Paint/Example 15 1:1.51 2100 2 3 4Paint/Example 16 1:4.36 2050 4 5 4

Comparative Experiment E Control Paint Example II

A control eggshell paint was prepared with an all acrylic latex havingDAAM composition with cross-linking functionality. A crosslinking agent,ADH is included in the formulation. All weights are in grams.

Grind: DI Water 153.1 Biocide 1 2.3 Biocide 2 2.8 Acrylic CopolymerDispersant 3 9.4 Potassium Carbonate 2.6 Titanium dioxide pigment 323.2Extender Pigment 6 22.7 Extender Pigment 1 39.7 Extender Pigment 2 56.7Extender Pigment 3 17.0 Extender Pigment 4 13.6 Extender Pigment 5 13.6Defoamer 2 1.1

Letdown: Phosphate Ester Surfactant, Ammonium Salt (25%) 2.3 NonionicSurfactant 3 2.3 Nonionic Surfactant 4 1.1 Anionic Surfactant 1 (60%)2.3 Coalescent 27.2 ADH 4.4 All Acrylic Control Latex with DAAM 453.6Styrene/acrylic copolymer 28.3 Hydrophobically modified polyetherrheology modifier 25 Polysiloxane modified resin 5.7 hydrophobicallymodified polyethylene oxide urethane 2 3.5 Defoamer 2 3.4 Defoamer 3 3.4DI Water 67The paint has a viscosity of 95 KU and an ICI of 1.746.

Paint Example (b) with Inventive Latex from Example 16

A paint composition using the latex of Example 16 was prepared byfollowing the paint formulation procedure of Control Paint Example II,except that (1) the Example 16 latex (486 g) was used instead of the allacrylic control latex with DAAM (453.6 g), (2) the ADH was left out ofthe formulation, (3) the amount of water used in the letdown was 34.6 ginstead of 67 g, (4) the amount of hydrophobically modified polyetherrheology modifier used was 10 g instead of 25 g, and (5) the amount ofhydrophobically modified polyethylene oxide urethane used was 1 ginstead of 3.5 g. The resulting paint composition had a viscosity of 102KU and 1.017 ICI.

Comparative Examples of Two-Part Crosslinking Vs. Invention Example

Water Scrub resistance (5 ID Crosslinkers (cycles) min.) Control PaintADH/DAAM 2200 3 Example II Paint (b)/Example 16 MAM/DAAM 2350 3 (1:4.36)

Example 17

To a 5-liter 4-necked round bottom glass reactor equipped with amechanical stirrer, a thermocouple, a condenser, and nitrogen purge, 600g of DI water, 2.1 g of sodium (C₁₄-C₁₆) olefin sulfonate, and 1.5 g ofsodium bicarbonate were added and then heated to 82° C. The followingsurfactants and monomers were made into a pre-emulsion throughagitation, 91.0 g of pre-emulsion and 2.6 g of KPS were charged to thereactor and heated for 20 minutes, and the rest of the pre-emulsiontogether with 91 ml of 1.0% KPS solution were delay fed in about threehours. After a one-hour hold at 84.0° C., the batch was cooled down to65° C. and t-BHP/FF6 (Bruggolite® FF6, Disodium salts of2-Hydroxy-2-sufinatoacetic acid and 2-Hydroxy-2-sufonatoacetic acid)chasers were added, and the pH of the latex was adjusted to about8.0-8.5 using aqueous ammonia concentrate (28%). The latex sample wasthen ready for paint evaluations.

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 675.5 g Butyl acrylate (BA) monomer606.0 g Methacrylic acid (MAA) monomer  14.0 g Methacrylamide (MAM)monomer  4.2 g Diacetone acrylamide (DAAM) monomer  18.2 gN-(2-methacryloyloxyethyl)ethylene urea Wet adhesion monomer (50%)  30.6g Ammonia (28%)  1.7 g DI water 540.0 g Branched alcohol Ethoxyphosphate (25%)  53.6 g Sodium olefin sulfonate (40%)  16.4 g

Example 18

The latex was made by following a similar procedure as Example 17 usingthe following pre-emulsion compositions:

Monomer Pre-Emulsion Composition

Methyl methacrylate (MMA) monomer 676.5 g Butyl acrylate (BA) monomer603.0 g Methacrylic acid (MAA) monomer  14.1 g Methacrylamide (MAM)monomer  5.1 g Diacetone acrylamide (DAAM) monomer  22.5 gN-(2-methacryloyloxyethyl)ethylene urea Wet adhesion monomer (50%)  30.6g Ammonia (28%)  1.8 g DI water 540.0 g Branched alcohol Ethoxyphosphate (25%)  53.6 g Sodium olefin sulfonate (40%)  16.4 gMolecular weight increases for the same latex samples after the 7 daycure

Mw Mw after MAM:DAAM before 7 days Particle ID (weight ratio) cure cure*pH size Solids Example 17 1:4.33 161,000 178,000 8.5 130 nm 49.2%Example 18 1:4.41 159,200 180,300 8.3 132 nm 49.2% *Mw for the after7-day cure came from the souble portion only.

While it is apparent that the illustrative embodiments of the inventiondisclosed herein fulfill the objectives stated above, it is appreciatedthat numerous modifications and other embodiments may be devised bythose skilled in the art. Therefore, it will be understood that theappended claims are intended to cover all such modifications andembodiments, which would come within the spirit and scope of the presentinvention.

We claim:
 1. An aqueous composition comprising latex particlescomprising a film forming monomer, a C₄-C₁₈ ethylenically unsaturatedmonomer moiety containing a ketone and a C₃-C₁₈ ethylenicallyunsaturated monomer moiety containing a primary amide, wherein theketone is substantially unreactive to the primary amide when the latexparticles are in water and wherein the ketone reacts with the primaryamide and latex particles crosslink when water is at least partiallyremoved from the latex under ambient conditions.
 2. The aqueouscomposition of claim 1, wherein the monomer containing a ketone isdiacetone acrylamide, diacetone methacrylamide, or acetoacetoxyethylmethacrylate.
 3. The aqueous composition of claim 1, wherein the monomercontaining a primary amide is methacrylamide or acrylamide.
 4. Anaqueous composition comprising film forming latex particles havingcrosslinking moieties, wherein the crosslinking moieties comprise adiacetone acrylamide moiety and a methacrylamide moiety, wherein thelatex particles cross-link when applied to a substrate at ambientconditions.
 5. The aqueous composition of claim 4 further comprisingstyrene.
 6. The aqueous composition of claim 4, wherein the compositionis substantially free of adipic acid dihydrazide or the like.
 7. Theaqueous composition of claim 4, wherein the film forming latex particlescomprise acrylic latex particles.
 8. The aqueous composition of claim 7,wherein the film forming latex particles comprises at least about 75%acrylic or vinyl monomers.
 9. The aqueous composition of claim 4,wherein the ratio by weight of diacetone acrylamide to methacrylamideranges from about 20:1 to about 1:20 by weight.
 10. The aqueouscomposition of claim 4, wherein the ratio by weight of diacetoneacrylamide to methacrylamide ranges from about 6:1 to about 1:3.
 11. Theaqueous latex composition of claim 4, wherein the ratio by weight ofdiacetone acrylamide to methacrylamide ranges from about 4:1 to about1:2.
 12. The aqueous latex composition of claim 4, wherein the latexparticles are polymerized from film forming monomers, wherein a ratio byweight of diacetone acrylamide and methacrylamide to the film formingmonomers ranges from about 0.1:100 to 10:100.
 13. The aqueous latexcomposition of claim 12, wherein the ratio ranges from about 0.5:100 to5:100.
 14. The aqueous latex composition of claim 12, wherein the ratioranges from about 1:100 to 3:100.
 15. The aqueous latex composition ofclaim 4, wherein the latex particles have a molecular weight from about20K to about 500K Daltons based on GPC measurement.
 16. The aqueouslatex composition of claim 4, wherein the latex particles have amolecular weight from about 80K to about 300K Daltons based on GPCmeasurement.
 17. The aqueous composition of claim 4, wherein the latexparticles have a MFFT from about −10° C. to about 50° C.
 18. The aqueouscomposition of claim 4, wherein the latex particles have a MFFT fromabout −5° C. to about 25° C.
 19. An aqueous composition comprising coreshell latex particles having a shell polymer comprising diacetoneacrylamide and methacrylamide moieties, wherein the latex particlescrosslink when applied to a substrate at ambient conditions.
 20. Theaqueous composition of claim 19, further comprising a core polymerhaving a diacrylate crosslinker.